1. Field of the Invention
The present invention generally relates to an organic digesting system incorporating a pair of digester units each of which includes an elongated, horizontally disposed frusto-conical, stationary outer drum with each outer drum including a correspondingly frusto-conical inner drum that is rotatably driven about a horizontal axis. The outer upper drum includes an inlet at the smaller end thereof and a vertical discharge conduit at the larger end thereof which communicates with the smaller end of the lower outer drum. The larger end of the lower outer drum includes a discharge outlet or conduit. Each of the inner conical drums is constructed of foraminous material to form a periphery that is porous with the foraminous periphery of the inner drum being supported from support shafts at each end thereof. The interior of the inner drum is provided with a plurality of inwardly extending agitation blades which are spaced peripherally on the interior of the inner drum and arranged in longitudinally spaced arrays. Also, each inner drum is provided with a plurality of outwardly extending outer agitation blades with the function of these blades being to mix, agitate and churn the organic material while lifting and moving it from the entrance to the upper outer drum to the discharge into the lower outer drum and to the discharge outlet from the lower outer drum.
2. Description of the Prior Art
U.S. Pat. No. 2,864,672 discloses an organic waste reduction apparatus incorporating a pair of stationary outer drums which are oriented one above the other with the drums being frusto-conical in configuration and including an entrance at the smaller end of the upper drum, a discharge from the larger end of the upper drum into the smaller end of the lower drum and a discharge from the larger end of the lower drum with agitating devices being rotatably supported in each of the drums and driven about a horizontal axis. The following U.S. patents also relate to this field of endeavor.
33,908 PA1 1,015,796 PA1 2,178,818 PA1 2,823,106
U.S. Pat. No. 33,908 discloses a structure for rotating a drum or barrel but is not relevant to the structure and function of the present invention. U.S. Pat. No. 1,015,796 discloses a drying apparatus having a rotatable drum with projecting blades thereon that is for a totally different function as compared to the present invention. U.S. Pat. No. 2,178,818 discloses a digester for organic waste that includes a structure that is totally different from that of the present invention. U.S. Pat. No. 2,823,106 discloses a process of fermenting waste which involves a rotatable drum used to screen composted material at the end of the composting process. The device disclosed in U.S. Pat. No. 2,823,106 is entirely different in mechanical apparatus and principle of operation as compared to this invention.
None of the above discussed prior patents discloses the drum arrangements of this invention including a frusto-conical shape and the most necessary thermo-chambers for a closed vessel technique including the inner conical drums of screen material having an interior array of blades and an exterior array of blades associated with the inner rotatable drum. This structure and the treatment procedure of organic material provides an efficient digesting system requiring a minimum of power to operate that is accomplished by the use of gravity in assisting movement of the organic material through the digesting system.